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https://issues.apache.org/jira/browse/MAPREDUCE-6361?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14540032#comment-14540032
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Tsuyoshi Ozawa commented on MAPREDUCE-6361:
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+1, I confirmed that this is a bug about concurrency between threads of
Fether#run as Junping mentioned. Committing this shortly.
> NPE issue in shuffle caused by concurrent issue between copySucceeded() in
> one thread and copyFailed() in another thread on the same host
> -----------------------------------------------------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-6361
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-6361
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Reporter: Junping Du
> Assignee: Junping Du
> Priority: Critical
> Attachments: MAPREDUCE-6361-v1.patch
>
>
> The failure in log:
> 2015-05-08 21:00:00,513 WARN [main] org.apache.hadoop.mapred.YarnChild:
> Exception running child :
> org.apache.hadoop.mapreduce.task.reduce.Shuffle$ShuffleError: error in
> shuffle in fetcher#25
> at
> org.apache.hadoop.mapreduce.task.reduce.Shuffle.run(Shuffle.java:134)
> at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:376)
> at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:163)
> at java.security.AccessController.doPrivileged(Native Method)
> at javax.security.auth.Subject.doAs(Subject.java:415)
> at
> org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1628)
> at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:158)
> Caused by: java.lang.NullPointerException
> at
> org.apache.hadoop.mapreduce.task.reduce.ShuffleSchedulerImpl.copyFailed(ShuffleSchedulerImpl.java:267)
> at
> org.apache.hadoop.mapreduce.task.reduce.Fetcher.copyFromHost(Fetcher.java:308)
> at
> org.apache.hadoop.mapreduce.task.reduce.Fetcher.run(Fetcher.java:193)
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